Most people don’t know this but windshield mount GPS and cell phones are illegal in California. Not totally illegal, but to comply with the law it’s unusable. It’s another one of those stupid laws by those who hate electronics and want to blame everything on gizmo owners.
You can only mount your GPS to the windshield on the driver’s side in the lower 5″ corner of the windshield, or the lower 7″ corner on the passenger side. The problem is that these are touch screen devices so on many modern cars you can’t reach the screen. My car’s windshield has such an extreme slope that the GPS would never fit there. And if it did the power cable would never reach.
Because you can’t mount it on the windshield if you use a GPS you have to take your eyes off the road to use the GPS which makes them far more dangerous than on the windshield.
So in their attempt to increase safety, it actually has the opposite effect.
You can however block a 5″x5″ section of your windshield for a toll transponder. When it comes to collecting money California says screw safety.